The job of an actor is to disappear into a variety of characters over several decades. But this process is complicated when a particular standout role remains in viewers' memories for that length of time. Philip Glenister's performance as a compromised lawyer in next week's BBC1 drama Hidden has been widely publicised along the lines of "what Gene Hunt did next", with Glenister asked at least as many questions about the old role as the new one.

This emphasis is inevitable because the audience's memory of screen appearances is exceptionally intense. Few classical actors become known forever as John "Hamlet" Smith; but appear in one TV hit and, even 40 years later, canny theatre producers stick the name of the cop or doctor you once played in brackets on the posters to encourage fans to buy tickets.

Some actors come to so resent a past TV part that they try to redact that paragraph from their CV. "He feels he's said enough about Taffy in Police Dog Handler", the publicist will murmur.

Well, nobody wants an old photo constantly held up against their face. But it is probably more sensible to accept and celebrate the endurance of great TV images. Derek Jacobi and Tim Pigott-Smith, recent fine King Lears in theatre, were happy, when promoting those productions, to discuss as well the significance to their careers of I, Claudius and The Jewel in the Crown.

Luckily, viewers are increasingly sophisticated about the fact that acting is a benign multiple personality disorder. Gone are the days when stars in TV shows feared (with some justification) that leaving the role for someone else would be viewed as a sort of adultery. David Tennant, for example, played several high-profile parts both during and immediately after his Tardis spell.

Glenister is also a sufficiently varied actor to make his Harry Venn in Hidden interesting for an audience that has switched on because of who he was in Life on Mars and Ashes to Ashes. Fittingly, given the plotline of those shows, there is an afterlife beyond DCI Hunt.